I use both regular oil paint (mostly Jackson’s) and water miscible (W&N Artisan) To my amazement, I have found that you can mix them as long as you don’t add water. My main criticism of the water miscible ones is that they lack body, very hard to do impasto. The other thing is that the white never seems to dry in a realistic period of time.
Linda, I have been using water-miscible oil paint for the last few years and I have found that, as with any oil paint, they differ between one maker and another. I do find some W&N Artisan paints to be a little 'stiff'. Predominantly I use Cobra (by Talens) which are quite 'buttery' and work well straight from the tube. Cobra has a Painting Paste that increases the volume for doing impasto and there may be something similar from W&N.
Alan, no it was NOT you (nor anyone on this forum) who said that white spirit was safer than Turps. And of course I agree with your comments - if you're going to use solvents, use little, and keep well ventilated. The latter's a bit difficult where I live.
Linda, yes, you can indeed mix water miscible oils with regular oil paint - I'm not sure why you would: because the sole advantage I can see in Artisan, Cobra, and the few other varieties of water-miscibles, is that you can clean up with water. But as I've done it myself .... I wonder why I did; cost, probably, at the time. Artisan paints were cheaper than the alternative. The only water-miscible paint I ever got on with at all was made by Grumbacher, and I've not seen it about lately.
One of my other hobbies, (before my illness) was woodworking. I used MDF occasionally for kitchen cupboard backs and sometimes for shelves. I also found that 5mm thickness MDF was a good surface for oils and acrylics. Usually I prime MDF with acrylic primer, with the addition of a little whiting powder. This helps reduce oils drying time; although too much can result in the surface of the painting looking chalky. Also best to mix the whiting to the consistency of single-cream before you add it to the primer, to avoid lumps. Some artists on Youtube use Moisture Resistant MDF by the way.
If I buy a whole 8 x 4 sheet, of MDF, my local 'sawmill' will cut the sheets for free, so I have a quantity in the size I need, and they fit conveniently into the boot. At some suppliers, you might have to pay for cutting, but it isn't usually a lot more.
For small, plein air size boards, 3mm thickness MDF is a good choice, and small boards are easily covered with canvas. (Old table cloths or bed sheets for instance; even patterned ones! You're going to prime them remember!) I found linen sheets in Birmingham's Rag Market, to be much cheaper than the same quantity of artists' linen. Just be sure it really is linen if you want to use it for serious work.
Any problems with warping are easily solved by backing the boards with sugar paper, or a heavy grade cartridge paper. The last time I did this a 3mm board cost me £18.00 and I had the board converted into 8, 24 x 20 panels.(With a bit left over!) Compare that to buying the same sized ready-made panels. And framing MDF is a doddle for the framer!
You can also use calico, which isn't so expensive as linen. It just needs careful priming if you are using oils. Even fine hessian is satisfying to paint on, if you like a rougher surface. I suppose you could paint on painters' dust sheets too, but these might be man-made 'linen'. For plein air sketching there's cotton, linen, duck, and genuine sail cloth. All good surfaces. (I used my old RN whites for some 16 x 20 inch boards some years ago! )
For gluing, use Evostick Resin W, (PVA wood glue). PVA glue watered down to a thin creamy mixture is also fine as a transparent primer, if you want to retain the canvas colour and grain. It will also serve as an alternative to animal-size. if animal products bother you. The commercial equivalent of thinned out PVA is called Unibond.
The only down side to DIY covering boards is the preparation, but with practice it soon becomes a speedier process.
For starters, try it on a couple of 40 x 30cm MDF boards. You should be able to buy off-cuts for this size.
I've gone on a bit here, but I hope this will help anyone who wants to try it.
Almost forgot; 12 mm thick MDF makes great painting-boards for working on watercolour paper